Comparative evaluation of Luminex based assays for detection of SARS-CoV-2 antibodies in a transplantation laboratory.

BACKGROUND: Detection of SARS-CoV-2 antibodies is essential in establishing the parameters of an individual's immune response to COVID-19, from both natural infection and vaccination. Despite this, there is currently limited clinical guidance or recommendations for serological methods for their measurement. Here, we evaluate and compare four Luminex-based assays for the multiplex detection of IgG SARS-CoV-2 antibodies. METHODS: The four assays tested were Magnetic Luminex Assay, MULTICOV-AB Assay, Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay and LABScreen COVID Plus Assay. Each assay's ability to detect antibodies to SARS-CoV-2 Spike (S), Nucleocapsid (N) and Spike-Receptor Binding Domain (RBD) was evaluated using 50 test samples (25 positive, 25 negative), previously tested by a widely used ELISA technique. RESULTS: The MULTICOV-AB Assay had the highest clinical performance detecting antibodies to S trimer and RBD in 100% (n = 25) of known positive samples. Both the Magnetic Luminex Assay and LABScreen COVID Plus Assay showed significant diagnostic accuracy with sensitivities of 90% and 88% respectively. The Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay demonstrated limited detection of antibodies to the S antigen resulting in a sensitivity of 68%. CONCLUSION: Luminex-based assays provide a suitable serological method for multiplex detection of SARS-CoV-2 specific antibodies, with each assay able to detect antibodies to a minimum of 3 different SARS-CoV-2 antigens. Assay comparison identified there is moderate performance variability between manufacturers and further inter-assay variation of antibodies detected to different SARS-CoV-2 antigens.

BSHI/BTS guidance on crossmatching before deceased donor kidney transplantation.

All UK H&I laboratories and transplant units operate under a single national kidney offering policy, but there have been variations in approach regarding when to undertake the pre-transplant crossmatch test. In order to minimize cold ischaemia times for deceased donor kidney transplantation we sought to find ways to be able to report a crossmatch result as early as possible in the donation process. A panel of experts in transplant surgery, nephrology, specialist nursing in organ donation and H&I (all relevant UK laboratories represented) assessed evidence and opinion concerning five factors that relate to the effectiveness of the crossmatch process, as follows: when the result should be ready for reporting; what level of donor HLA typing is needed; crossmatch sample type and availability; fairness and equity; risks and patient safety. Guidelines aimed at improving practice based on these issues are presented, and we expect that following these will allow H&I laboratories to contribute to reducing CIT in deceased donor kidney transplantation.